There is a leap lunar month after the 4th month in the Chinese Civil Calendar year 2001. The Chinese Civil Calendar is the official calendar announced by the China, Taiwan and Hong
Kong governments
using the time zone of east longitude 120th degree.

When calculating the Chinese Civil Calendar for the time zone of west longitude
75th degree Eastern Standard Time (EST), the leap month of year 2001 is after the
4th lunar month, which is same as the China time zone. When calculating
the Chinese Astronomical Calendar for EST, the leap month of year 2001 is after the
5th lunar month.

The following explanation can help you to know why. There
are three basic rules for the Chinese Calendar.

The following is the listing of dates and times about new moon days and the Solar Center points. A lunar month not
containing a Center Point is a Leap month.

2001 US EST Civil Calendar

Month Name

New Moon Date/Time

Zodiac Date/Time

Zodiac Month

3rd Lunar Month

03-24 20:21

04-04 12:24

Clear and Bright (Dragon Month)

04-19 19:36

Grain Rains (Taurus) - Center Point

4th Lunar Month

04-23 10:26

05-05 05:45

Start of Summer (Snake month)

05-20 18:44

Grain Fills (Gemini) - Center Point

Leap
4th Month

05-22 21:46

No Center point

06-05 09:54

Grain in Ear (Horse Month)

5th Lunar Month

06-21 06:58

06-21 02:58

Summer Solstice (Cancer) - Center Point

07-06 20:07

Slight Heat (Sheep Month)

6th Lunar Month

07-20 14:44

07-22 13:26

Great Heat (Leo) - Center Point

08-07 05:52

Start of Autumn (Monkey Month)

7th Lunar Month

08-18 21:55

The first day of the leap 4th month is on
5-22-01 and the last day of this month is on 06-20-01. There is no Center
Point in this month. Therefore this month is a Leap Month. The name of the leap
month uses the previous month name.

The first day of the 5th lunar month is on
6-21-01, which is the same day as the Summer Solstice (Center Point). In the rule
of the Chinese Civil Calendar, the 5th lunar month includes the Center Point.
Therefore, the 5th lunar month is not a leap month.

2001
US EST Astronomical Calendar

Month Name

New Moon Date/Time

Zodiac Date/Time

Zodiac Month

4th Lunar Month

04-23 10:26

05-05 05:45

Start of Summer (Snake month)

05-20 18:44

Grain Fills (Gemini) - Center Point

5th Lunar Month

05-22 21:46

06-05 09:54

Grain in Ear (Horse Month)

06-21 02:58

Summer Solstice (Cancer) - Center Point

Leap 5th Month

06-21 06:58

No Center point

07-06 20:07

Slight Heat (Sheep Month)

6th Lunar Month

07-20 14:44

07-22 13:26

Great Heat (Leo) - Center Point

08-07 05:52

Start of Autumn (Monkey Month)

7th Lunar Month

08-18 21:55

In the theory of the Astronomical Calendar, the 5th lunar month, from 5-22-01 21:46 to 06-21-01 06:57, includes the Center Point of Summer Solstice time 06-21 02:58. Therefore, the 5th lunar month from 5-22-01 21:46 to 06-21-01 06:57 is not a leap month. The leap 5th month from 06-21-01 06:58 to 07-20-01 14:43 is a leap month because it contains no Center Point.

The Astronomical Calendar compares the dates and times of the new moon day and the Center Point. The Civil Calendar compares only the dates of the new moon day and the Center Point.